Presently available wheelchairs are all characterized in that the seat frame is normally part of the main frame of the chair that supports the wheels. As a consequence, severe limitations are placed on any type of adjustments of the chair for optimum comfort of a patient. For example, if the center of gravity of the chair with a patient seated therein is to be shifted, it is necessary in some manner to change the horizontal distance between the seat and the rear wheels. Since the seat is normally a part of the frame, this adjustment is presently being made by actually shifting the rear wheels on the main frame of the wheelchair. For example, by shifting the rear wheels to a position closer to the seat, the center of gravity is effectively positioned closer to the main wheels.
Further adjustments of the seat such as tilt can only be effected with present day chairs by again changing the main wheels. For example, the level of the main wheels can be shifted by shifting the axle position on the main frame, while maintaining the caster wheels at their pre-existing positions.
In wheelchairs it is a desirable feature to be able to adjust the camber of the main wheels; that is, the angle that the plane of these wheels makes with the vertical. Such camber adjustment at the present time is made by washers. This adjustment requires taking the wheels apart and inserting washers to provide for the desired camber. The adjustment is time consuming and the final positions can only be done in steps rather than providing for a smooth camber adjustment to a desired angle.
There is a real need at the present time for a vastly improved ultra light high performance wheelchair wherein numerous adjustments of the seat relative to the frame can be effected without having to change the position of the main wheels on the frame. Further, there is a need for enabling a simple camber adjustment of the wheels to be realized so that such adjustment can be effected without having to disassemble the wheelchair and wherein adjustment in integral steps is avoided.